[13.3] nutrient cycles (2/2) the phosphorus cycle

Question 1

what is phosphorus used in? [7]

Answer 1

• phospholipids
• ATP
• nucleic acids
• NAD
• NADP
• FAD
• acetyl CoA

Question 2

what form of phosphate do organisms usually use?

Answer 2

phosphate ion form (PO₄³⁻)

Question 3

describe the phosphorus cycle

Answer 3

• dissolved phosphate ions in oceans, lakes, and soils ➞ phosphate ions in plants via absorption
• dissolved phosphate ions ➞ phosphates in rocks via sedimentation
• phosphate ions in plants ➞ phosphate ions in animals via feeding and digestion
• phosphate ions in animals ➞ phosphate ions in wastes and remains eg. guano, bones and shells via excretion and decomposition
• phosphate ions in animals ➞ dissolved phosphate ions in oceans, lakes, and soils via excretion
• phosphate ions in waste and remains ➞ dissolved phosphate ions in oceans, lakes, and soils via erosion
• phosphate ions in wastes and remains ➞ phosphates in rocks via deposition
• phosphates in rocks ➞ dissolved phosphate ions in oceans, lakes, and soils via erosion and use of fertilisers

Question 4

describe the role of microorganisms in the phosphorus cycle (2)

Answer 4

• function as decomposers / saprobionts
• that break down the molecules in dead organisms to release phosphate ions into the ground